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There isn't a lot of information about the L4 cache, but as far as I know, it was used in the 4th and 5th generation of Intel processors(2013-2014), but it's gone from the current generation.
Was the L4 bad, ineffective or something?
812
asked Nov 29 '16 11:11
L4 cache in real systems eDRAM is expensive as well. For all these reasons, L4 cache is not popular today and is used in specific processors only and these processors are mainly targetted towards low-powered laptops or mobile devices. Hence, L4 cache is not available in all Intel processors.
L4 cache is currently uncommon, and is generally on (a form of) dynamic random-access memory (DRAM), rather than on static random-access memory (SRAM), on a separate die or chip (exceptionally, the form, eDRAM is used for all levels of cache, down to L1).
Deleting or clearing your cache memory will wipe your computer clean of all the repeated tasks you perform on your device.
Level 3 (L3) cache is specialized memory developed to improve the performance of L1 and L2. L1 or L2 can be significantly faster than L3, though L3 is usually double the speed of DRAM. With multicore processors, each core can have dedicated L1 and L2 cache, but they can share an L3 cache.
For Haswell and Broadwell, eDRAM L4 cache tags are resident in the on-chip L3 cache. Although this setup simplifies the LLC design and allows earlier tag checking for fetches from the processor, it makes the accessing to eDRAM LLC from other devices (e.g., independent GPUs via PCIe) slower as these memory requests have to be forwarded to on-chip L3 first before being handled by the LLC. To address this, eDRAM has been moved to the position upon DRAM controllers in Skylake (more like a memory-side buffer rather than a cache)
Reference : Li, Ang, et al. "Exploring and analyzing the real impact of modern on-package memory on HPC scientific kernels." Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis. ACM, 2017
You can see Broadwell, Haswell, and Skylake architectures below.
Broadwell and Haswell
Skylake
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answered Sep 20 '22 15:09
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